Double knit, or bi-ply, fabrics have been knitted together for over a century. One of the earliest of these fabric constructions (U.S. Pat. No. 709,734) comprises two knitted fabric webs that are united by stitches causing the yarn in one of the webs to engage the other web at specified intervals. The bi-ply fabric produced thereby was found to exhibit several desirable characteristics, including the ability to have one web, or face, formed from one type of yarn, and the other web formed of yarns of a distinctly different type. The earliest of these bi-ply constructions included a wool outer face and a cotton inner face, providing the combination of warmth and comfort.
Over the past one hundred years, various constructions of bi-ply fabrics have evolved, with particular emphasis on creating specific characteristics in each ply of the fabric that could not be achieved in either ply alone. In more recent years, bi-ply fabric constructions have been developed to take advantage of other features that can be accomplished with the known bi-ply constructions. For example, U.S. Pat. No. 5,373,713 to Miller discloses a bi-ply structure where one web is formed with thin and thick yarns grouped in adjacent courses, where the grouped courses are alternated to produce a ridged effect in the fabric. The thick yarns produce ridges and the intermediate thin yarns produce air entrapment channels in one web. These air entrapment channels provide a double layer of insulating air, one layer at the inside surface of the fabric and the second layer within the interior of the fabric.
There is also known a method of alternating interlock stitches in a bi-ply construction to produce a series of individual air pockets arranged in a checkerboard pattern on the inner layer of the fabric. This construction, however, does not permit air movement or channeling between the overlying webs.
What is needed is a bi-ply construction wherein both webs of the fabric may be formed of similarly sized yarns and similar yarn materials, while providing air channels for movement between the two plies of the fabric construction.
There are also known in the art specialty garments having functional aspects intended to address particular known problems. For example, there is known a garment having an electronic heating control system incorporate therein. There are also known specialty garments that incorporate physiological monitoring or medicinal stimulation to a wearer. Each of these very specific garment constructions addresses one particular known problem; however, they provide little or no other known utility. What is also needed, therefore, is a multi-purpose, multi-functional fabric and apparel.